The invention relates to a method for attaching a joining element to a deformable flat material or workpiece or to a rivet joint or connection and to a joining or function element for connecting same to a flat material.
Methods for the attaching and/or fixing of function elements, especially of connecting elements, such as nuts, bolts or similar elements to a flat material, for example to a workpiece manufactured from a flat material, are known in various embodiments. In particular, a method is known in which the attachment or fixing of the respective function element takes place by riveting in the area of a dome-shaped section manufactured from the flat material by permanent or plastic deformation, i.e. by drawing or pressing (EP 539 793 B1). In this prior disclosed method, after joining and during riveting of the rivet collar provided on the function element, the dome-shaped section is reshaped so that the diameter of the joining opening in the flat material is reduced and its edge is pressed to produce radial pressure ring tension on the rivet collar, namely for the purpose of additional anchoring. However, this prior method requires a relatively elaborate tool. Further, it has proven that, contrary to expectations, this method does not achieve a substantial improvement in the anchoring, i.e. especially the pull-out strength of the function element in the workpiece or in the flat material.
It is an object of the invention is to present a method that can be implemented with simplified means while nevertheless enabling anchoring of function elements in a flat material with high pull-out strength.